The present invention relates to assignment of addresses to stations on a network such as the public switched telephone network. More particularly, it relates to a method and a network comprising switches and database management systems for implementing such method, for assigning destination addresses, e.g. telephone numbers, to stations on the network without regard to rate areas in which the stations are located.
Currently, it is anticipated that the North American Numbering Plan (NANP) will reach exhaustion in the near future, perhaps as early as the year 2007. The NANP uses a 10 digit telephone number format for end user network addresses, i.e. telephone numbers, and eventually continued growth of the telephone network will exhaust the NANP, making it necessary to enlarge the telephone number format. This change will have a major impact. Everything that uses a telephone number will be affected. Major expenditures to accommodate the new format will be required worldwide. All countries using NANP must agree to the new format and to a transition method. Various national regulators must then order the agreed solution and then years will be required to implement the necessary hardware changes. Even the cutover period may be spread over an extended interval. While it is important to decide as soon as possible how the NANP expansion will be accomplished, it is also important to defer actually implementing the expansion as long as possible. The present value of the expansion""s cost shrinks the longer the expansion can be delayed and the actual cost can actually be reduced since the changes required to implement the NANP expansion can be included in the normal modernization of equipment.
While the growth in use of the network drives the exhaustion of the NANP and is expected to reach a point where more than the 10 billion currently possible numbers will be needed, inefficiencies in the way numbers are assigned will hasten that date. Particularly, the use of numbers in the NANP to identify not just particular stations on the network but also the geographical area where the stations are actually located; and the manner in which numbers are assigned to particular geographical areas, can result in numbers being xe2x80x9cstrandedxe2x80x9d in low-growth areas where they are unlikely to be assigned to an end user in the foreseeable future. An extreme example of this problem occurs in one area code where the assignee of the present invention uses approximately 7% of the numbers assigned.
A rate area is a geographic area represented by a single point, the xe2x80x9crate centerxe2x80x9d. The rate center is used to represent the physical location of all end users located within the rate area. Distance is calculated between the calling station and the called station based on the rate centers associated with each station. Groups of rate areas form a station""s calling area. Local calling plans for end users are usually defined as calls between certain pairs of rate areas. Rate areas determine whether inter-carrier settlements are done for local or toll traffic minutes. This is an important distinction as xe2x80x9ctollxe2x80x9d access minutes cost about 3 times as much as xe2x80x9clocalxe2x80x9d traffic minutes. Rate areas are thus very important to local service providers. Currently, the first 6 digits of a 10 digit telephone number, hereinafter sometimes NPA-NXX, nominally indicate the rate area in which the identified rate station is located. Carriers comprised in the network rely on the NPA-NXX of a called telephone number to identify the called station""s associated rate area and thus each NPA-NXX must correspond to only one rate area.
Typically, though not necessarily, the NPA-NXX of a number is also used to identify the switch serving the called station in order to route the call through the network, as will be described further below. Within a given area code (NPA) an office code (NXX) is assigned to a switch and to a rate area served by that switch. That is, the 10 thousand numbers defined by the last 4 digits are assigned by the network administrator to a particular switch and a particular rate area served by that switch. In rate areas that are growing slowly, or are served by a large number of carriers, assignment of numbers in blocks of 10 thousand can result in a large fraction of xe2x80x9cstrandedxe2x80x9d numbers.
To address this problem a xe2x80x9cthousand-block number poolingxe2x80x9d method of number assignment has been implemented in the telephone switched network. Blocks of one thousand numbers are xe2x80x9cportedxe2x80x9d from the switch normally associated with an NXX to another switch serving the same rate area. This breaks the relation between NPA-NXX and the switch, and calls are routed based on pointers (LRN""s) associated with the ported numbers in a database maintained by the network Administrator. It has recently been proposed to extend this approach to the porting of individual telephone numbers.
While the above described approaches to number assignment have proven to be somewhat effective in increasing the utilization of numbers in rate areas served by more than one switch, xe2x80x9cnumber poolingxe2x80x9d approaches still require that particular NPA-NXX""s be associated with a single rate area with the result that large fractions of numbers assigned to low-growth areas can be strandedxe2x80x9d. Consequently, there is a need for a number assignment method, and a network adapted to such a method, which will allow the assignment of xe2x80x9cstrandedxe2x80x9d numbers without regard to rate areas in which stations are located, and thereby improve utilization of the NANP.
These and other needs are addressed by the present invention by means of a method and network, and computer-readable media carrying instructions for controlling the network to carry out the method. In accordance with an embodiment of the present invention a method for improving the utilization of numbers in a switched network, each of the numbers having an associated rate area, includes: a) requesting that a number not assigned to a station in the rate area nominally indicated by the number be ported to a switch serving a different rate area; b) storing information associating the number with the different rate area in a database; and c) thereafter, providing the associating information from the database in response to requests from switches which have received the number as a called number.
In accordance with an aspect of the invention the associating information includes a Local Routing Number.
In accordance with an another aspect of the invention the method further includes a) defining a group of numbers as portable; b) providing data identifying the group of numbers to switches routing calls to the switch serving the different rate area; c) controlling the routing switches to determine locally if a received called number is portable; and d) controlling the routing switches to request associating information for the received called number from the database only if the received called number is portable.
In accordance with an aspect of the invention the number is initially associated with a wireless network.
In accordance with an aspect of the invention the routing switches are further programmed to determine the rate area directly from the number if accessing the database system does not determine a rate area associated with the number.
In accordance with an another aspect of the invention a switched network including: a) a first wire center serving a destination station; b) a billing system for determining if calls are local or toll, end user charges, and carrier settlement amounts; c) a database system including a network database and a network database manager, the database manager being programmed to receive and maintain in the network database information associating numbers that are not assigned to stations in rate areas nominally indicated by the numbers with different rate areas; and d) a second wire center communicating with the first wire center, the database system, and the billing system; the second wire center including a programmable switch; the switch being programmed to: d1) receive a called number identifying the destination station; d2) access the database system to determine a rate area associated with the destination station; d3) transmit billing information for the call to the billing system in accordance with the associated rate area; and d4) route the call to the first wire center.
In accordance with an another aspect of the invention the network includes a Number Portability Administration Center system communicating with database managers in a public switched network to receive information indicating when a number that is not assigned to a station is ported to a switch serving a rate area, and to provide information associating said number and said rate area to said network database manager.
In accordance with an still another aspect of the invention a computer-readable medium carries one or more sequences of one or more instructions for controlling a network database manager to reduce the fraction of numbers stranded in a rate area, the one or more sequences of one or more instructions including instructions which, when executed by one or more processors, cause the one or more processors to control said system to perform the steps of: a) receiving information associating numbers that are not assigned to stations in rate areas nominally indicated by the numbers with different rate areas; b)maintaining said associating information in a network database; and c) thereafter, providing said associating information from said network database in response to requests from switches which have received said numbers as called numbers.
In accordance with yet another aspect of the invention the a computer-readable medium carries one or more sequences of one or more instructions for controlling a Number Portability Administration Center system to reduce the fraction of numbers stranded in a rate area, the one or more sequences of one or more instructions including instructions which, when executed by one or more processors, cause the one or more processors to control said system to perform the steps of: a) communicating with database managers in a public switched network to receive information indicating when a number that is not assigned to a station is ported to a switch serving a rate area; b) providing information associating said number and said rate area to the network database managers.
Still other objects and advantages of the present invention will become readily apparent from the following detailed description, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.